Abstract
This paper presents time modulated beam steered antenna array without phase shifters. The beam steering is analyzed considering a two-element time modulated antenna array (TMAA) of printed dipoles with microstrip via-hole balun. The proposed array resonates at the Industrial, Scientific, and Medical (ISM) radio bands, 2.45 GHz and 5.8 GHz, and offers wide bandwidth inherited due to modified structure of ground plane. Array elements are excited by complex exponential excitation signal through broadband power divider and radio frequency (RF) switches to achieve amplitude and phase variation without phase shifters. Differential Evolution algorithm is used to modify the time sequences of the RF switches connected to the antennas to generate radiation pattern with optimum dynamic efficiency by suppressing sideband radiations. Also switch-on time instant of RF switch connected to the subsequent element is modulated to steer the beam towards different directions. The proposed prototype is fabricated followed by parametric optimization. The fabrication results agree significantly well with simulated results.
Highlights
Antenna arrays are widely used in communication systems to obtain desired radiation characteristics
The overall system consists of 2element printed dipole antenna array, radio frequency (RF) switches, pulse generator, power divider, and an analog multiplier
The antenna array, power divider, and RF switches are printed on the FR4 dielectric material of dielectric constant 4.4 and thickness 1.6 mm
Summary
Antenna arrays are widely used in communication systems to obtain desired radiation characteristics. The limitations associated with the phased array antenna to generate radiation patterns with various stringent designing constraints are cost, size, power consumption, and high complexity. Different optimization strategies have been used in TMAA to synthesize its radiated power pattern [8, 9] to realize beam steering [10], beam forming [11,12,13,14], null synthesis [15, 16], and direction finding [17] without using conventional phase shifters. The presented article proposes TMAA of printed dipoles for beam steering without using phase shifters. Application of complex exponential signal steers the beam towards different directions as the switching time sequences of RF switches are modulated.
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